PCI Express is an I/O (Input/Output) interconnect that attempts to be software compatible with PCI (Peripheral Component Interconnect). While trying to maintain some level of compatibility with PCI, PCI Express offers many features not found or fully supported by PCI. One such feature is the support of isochronous data transfers. Isochronous data transfer support may help multimedia applications such as, for example, audio and/or video playback applications achieve high quality results. However, the PCI Express implementation of isochronous data transfers has relaxed some of the stringent PCI ordering rules. As a result, a software application that isochronously transfers data via a PCI Express channel may need to utilize different techniques to track the progress of such a transfer than techniques used to track the progress of conventional PCI data transfers.